WO1998005510A2 - Method and system for reproducing color images as duotones - Google Patents
Method and system for reproducing color images as duotones Download PDFInfo
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- WO1998005510A2 WO1998005510A2 PCT/US1997/012835 US9712835W WO9805510A2 WO 1998005510 A2 WO1998005510 A2 WO 1998005510A2 US 9712835 W US9712835 W US 9712835W WO 9805510 A2 WO9805510 A2 WO 9805510A2
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
- B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
- B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
- B32B5/028—Net structure, e.g. spaced apart filaments bonded at the crossing points
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
- B41M3/008—Sequential or multiple printing, e.g. on previously printed background; Mirror printing; Recto-verso printing; using a combination of different printing techniques; Printing of patterns visible in reflection and by transparency; by superposing printed artifacts
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/46—Colour picture communication systems
- H04N1/56—Processing of colour picture signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/46—Colour picture communication systems
- H04N1/56—Processing of colour picture signals
- H04N1/60—Colour correction or control
- H04N1/6016—Conversion to subtractive colour signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/46—Colour picture communication systems
- H04N1/56—Processing of colour picture signals
- H04N1/60—Colour correction or control
- H04N1/6058—Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/46—Colour picture communication systems
- H04N1/56—Processing of colour picture signals
- H04N1/60—Colour correction or control
- H04N1/6097—Colour correction or control depending on the characteristics of the output medium, e.g. glossy paper, matt paper, transparency or fabrics
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
- B32B2262/02—Synthetic macromolecular fibres
- B32B2262/0253—Polyolefin fibres
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2305/00—Condition, form or state of the layers or laminate
- B32B2305/38—Meshes, lattices or nets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/54—Yield strength; Tensile strength
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/724—Permeability to gases, adsorption
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/726—Permeability to liquids, absorption
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/10—Scrim [e.g., open net or mesh, gauze, loose or open weave or knit, etc.]
- Y10T442/184—Nonwoven scrim
- Y10T442/197—Including a nonwoven fabric which is not a scrim
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/659—Including an additional nonwoven fabric
- Y10T442/66—Additional nonwoven fabric is a spun-bonded fabric
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/659—Including an additional nonwoven fabric
- Y10T442/668—Separate nonwoven fabric layers comprise chemically different strand or fiber material
Definitions
- the present invention generally pertains to printing full colored images using only two colors of ink, and more specifically, to a method and system employed for selecting the colors of the two inks that will be used and mapping colors from the full color image to the duotone colors so as to reproduce the full color image as closely as possible.
- Modern color reproduction typically employs a fixed set of process ink colors that include cyan, magenta, yellow, and sometimes black. Placed on top of one another and in juxtaposition, these inks can be used to reproduce a range of colors called their gamut. Although the standard process colors were carefully chosen to provide a relatively large gamut, this gamut is nevertheless quite limited when compared to the full range of colors visible to the human eye. Thus, color fidelity must generally be compromised when reproducing images with process colors (or any other small, fixed set of color inks). The problem is even more apparent when fewer than four color inks are used for printing an image.
- duotone process in which just two colored inks are used. While duotones obviously have more limited color gamuts than three- and four-ink processes, they can nevertheless be used to reproduce a surprising range of color.
- a duotone print is really a combination of four colors: the paper color alone, the colors of each of the inks individually, and the color of the two inks superimposed on each other. These four colors define a bilinear surface in color space that may span a broad range of the full color gamut.
- Duotone printing has traditionally been used almost exclusively to enhance monochrome gray-scale images with a tint of color.
- duotone printing is significantly less expensive than process color, typically about two-thirds the cost.
- a user can select one or both of the two printing inks to meet constraints, such as matching the precise colors of one or more corporate color inks.
- printed documents are often designed for just two inks, generally black (for text) and one additional color.
- any prior art teaches a general approach to reproducing images using duotones.
- the most closely related work in the field of computer graphics addresses the problem of gamut mapping, or smoothly mapping the colors of an original image to those available on an output device.
- a duotone gamut is much more restricted than the gamut of a typical output device.
- the mapping approaches disclosed in the prior art provide for mapping from a broader range of colors to a more limited gamut in three dimensions.
- the prior art does not disclose a process for mapping a three-dimensional gamut to a gamut comprising a two-dimensional surface.
- the prior art also discloses creating a "highlight color image," a specialized duotone in which one ink (of the two inks used) is black.
- Color and Color Spaces Color is determined by the intensity of light in the range of visible wavelengths from about 400 nm to 700 nm. According to the tristimulus theory of color perception, all colors can be reproduced using combinations of three primary wavelengths (roughly corresponding to red, green, and blue). Thus, color can be expressed as a function of wavelength, known as a spectral reflectance, or as a three-dimensional quantity.
- the XYZ color space was developed in 1931 by the Commission
- the XYZ color space is additive, meaning that the color resulting from the superposition of two colored light sources can be calculated by simply adding the coefficients of the two known colors.
- a spectral reflectance can be converted to XYZ coordinates by integrating the spectral information against three functions x, y, and z.
- the computer graphics community is more familiar with the RGB color space, an additive color space that is device dependent. Conversion between RGB and XYZ coordinates can be accomplished by a linear transform if the XYZ coordinates of the device's red, green and blue primaries are known.
- perceptually uniform color spaces allow the difference between two colors (as perceived by the human eye) to be measured as the distance between points. For example, two colors c ⁇ and c 2 , separated by some distance d in a perceptually uniform color space, appear about as different as two other colors c 3 and c 4 separated by the same distance d.
- the (CIE) developed two perceptually uniform spaces: L*a*b* and L*u*v*. Both color spaces require the definition of a reference white, which is usually taken to be a standard light source defined by the (CIE). In both spaces, L* indicates brightness and has a value of 100 for reference white.
- Color Halftone Printing In color halftone printing, a continuous-tone image is reproduced by printing a number of versions of the image atop one another. Each version, known as a halftone separation, consists of various sized dots of a single ink. Color halftone printing differs from color dithering on monitors in that subtractive effects as well as additive effects play a role. The subtractive effect of superimposing dots of different color produces the set of printing primaries for a particular set of inks.
- FIGURE 1 illustrates the reproduction of a full color image 30 using cyan, magenta, yellow, and black inks.
- a small square 32 is enlarged, and then a small square 34 in square 32 is again enlarged to show how dots of cyan, magenta, yellow, and black are printed to visually provide a full range of colors in the full color image.
- the "Neugebauer equations” express colors in terms of their coordinates in the XYZ color space.
- the Neugebauer model was originally designed to describe three-color printing, though it can be generalized to handle any number of inks. If g 0 is the color of the paper, g, is the color of ink / on the paper, g tj is the color of inks / andy superimposed on the paper, g lj k is the color of all three inks i,j, and k superimposed on the paper, and ⁇ , is the amount of ink i (between 0 and 1). For three inks, the Neugebauer model describes c, a color in the printing gamut, in terms of the eight printing primaries and the amounts of the three inks required to achieve c:
- the prior art does not teach mapping from a three-dimensional color space to the two-dimensional gamut used for duotone printing. More importantly, there is no teaching in the art of determining the best color inks from those that are available to print a duotone image corresponding to a full color image so as to most accurately retain the "appearance" (or other selected attributes) of the full color image. To provide more versatility in such a process, it would be desirable to enable a user to select one of the color inks and then automatically determine the other color ink that should preferably be used for printing the duotone image.
- duotone separations the ink colors used
- this capability could be useful for creating duotone separations of full-color images for printing in a "yellow pages" telephone directory.
- a method for producing a duotone image using only two colors.
- the duotone image corresponds to a full color image defined by color data.
- the method includes the steps of enabling a user to select from zero to two colors that will be used to produce the duotone image.
- a gamut is determined that includes any color selected by the user and is defined by the two colors that will be used for producing the duotone image. Each color that is not selected by the user for the gamut is automatically determined.
- the color data for the full color image is mapped onto the gamut to determine duotone data that define how the two colors are combined to produce the duotone image.
- the duotone data are determined so as to maximize preservation of selected predetermined attributes of the full color image in the duotone image.
- the method further includes the step of enabling the user to select a background color for the duotone image. If the user does not select a background color, a background color is automatically determined for the duotone image so as to maximize preservation of the selected predetermined attributes of the full color image in the duotone image.
- the step of mapping the color data preferably comprises the step of scaling luminance values for the full color image to a range of luminance values for the gamut.
- a relative luminance of the full color image is thus one of the plurality of predetermined attributes, and preservation of the relative luminance has the highest priority when mapping the color data for the full color image to the gamut.
- the step of mapping preferably comprises the step of scaling the predetermined attributes along two of three orthogonal axes, so that the predetermined attributes are disposed about the gamut.
- Two of the three orthogonal axes are respectively a relative luminance axis and a color variation axis.
- the step of scaling comprises the step of selecting a plurality of different values on the relative luminance axis as prospective origins of the color variation axis. For each value selected on the relative luminance axis, the color variation is scaled along a corresponding color variation axis.
- the method also includes the step of projecting a third axis that is orthogonal to the relative luminance axis and the color variation axis, by determining a cross product of the relative luminance axis and the color variation axis.
- the third axis at least approximates an average normal of a bilinear surface of the gamut.
- the step of automatically selecting each color not selected by the user preferably comprises the step of employing a simulated annealing technique that is sensitive to local minima.
- the method optionally includes the step of clustering colors in the full color image. Any clusters of colors that are outside the gamut are classified as outlying colors, which may not be considered in the step of mapping the color data for the full color image onto the gamut.
- the method may include the step of employing a black separation to produce the duotone image, in addition to the two colors.
- the method may also include the step of removing a portion of black from the full color image before the step of mapping the color data for the full color image. The black separation is then determined so as to restore to the duotone image at least some of a full range of luminance that is present in the full color image.
- the duotone image is produced using two colors.
- the system includes a memory for storing machine language instructions that define functions implemented by a processor when executing the machine instructions. These functions are generally consistent with the method discussed above.
- FIGURE 1 (PRIOR ART) is a full color image and two increasingly enlarged portions thereof;
- FIGURE 2 (PRIOR ART) is a conventional duotone gamut, which is a bilinear surface in additive color space;
- FIGURE 3 is a duotone gamut on which are shown three orthogonal axes used in mapping colors from a full color image to the duotone gamut, in accord with the present invention
- FIGURE 4 illustrates the orthogonal axes used for transforming the colors of a full color image into a duotone gamut and shows the image colors both before and after a luminance transformation has occurred
- FIGURE 5 illustrates the orthogonal axes used for transforming the colors of a full color image into a duotone gamut and shows the image colors both before and after a color variation transformation has occurred;
- FIGURE 6A is a graph showing a linear ink-spread transformation for a single himinance bin
- FIGURE 6B is a graph showing a Bezier curve used for ink-spread transformation, for a typical luminance bin
- FIGURE 7 illustrates the orthogonal axes used for transforming the colors of a full color image into a duotone gamut and shows the image colors (following the luminance and color variation transformations) both before and after a projection has occurred relative to the P axis
- FIGURE 8 is a black-enhanced duotone that is used when black ink is provided for printing a duotone image, in addition to the two colors of ink;
- FIGURE 9 includes four images showing the images at each step employed for producing a black-enhanced duotone image in accord with the present invention
- FIGURE 10A is a graph illustrating the reduction of black in a color
- FIGURE 1 OB is a graph illustrating the replacement of black in a duotone image color
- FIGURES 11 A-l ID are, respectively, a full color image of Cezanne's Blue Vase, a traditional (PRIOR ART) duotone image printed with PANTONE 130 and process black ink, a corresponding duotone image prepared using the present invention, and a black-enhanced duotone image prepared in accord with the present invention and printed using PANTONE 198, PANTONE 604, and PANTONE Process Black inks;
- FIGURES 12A and 12B are, respectively, a full color image of a koala and a duotone image produced in accord with the present invention and printed using PANTONE 144 and PANTONE 546 inks;
- FIGURES 13 A, 13B, and 13C are, respectively, a full color print of
- FIGURES 14A and 14B are, respectively, a full color print of a woman, and a corresponding duotone image produced using the present invention and printed with PANTONE 152 and PANTONE Process Blue inks;
- FIGURES 15A and 15B are, respectively, a full color print of a girl, and a corresponding duotone image produced using the present invention and printed with PANTONE 152 and PANTONE Process Blue inks;
- FIGURES 16A and 16B are, respectively, a full color print of three boys, and a corresponding duotone image produced using the present invention and printed with PANTONE 152 and PANTONE Process Blue inks;
- FIGURES 17A, 17B, and 17C are, respectively, a full color print of a sunset, a corresponding duotone image produced using the present invention and printed with PANTONE 151, PANTONE 246, and PANTONE Process Black inks, corrected to match the process-color print in FIGURE 17A, and, a corresponding duotone image produced using the present invention and printed with the same inks as FIGURE 17B, but without correction in order to obtain colors outside the gamut of process color printing;
- FIGURES 18A and 18B are, respectively, a full color print of Schiele's Agony, and a corresponding duotone image produced using the present invention and printed with PANTONE 329 and PANTONE Warm Red inks on yellow paper;
- FIGURE 19 is a flow chart showing the steps used for mapping color data from a full color image to a duotone gamut
- FIGURE 20 is a flow chart showing the logical steps used for applying simulated annealing to determine pairs of colors for use in defining a duotone gamut;
- FIGURE 21 is an isometric view of a generally conventional graphics workstation suitable for implementing the present invention.
- FIGURE 22 is block diagram showing internal components of the workstation of FIGURE 22.
- the Neugebauer model describes c, a color in the printing gamut, in terms of the four printing primaries and the amounts of the two inks, g, and g 2 :
- the gamut described by the above equation is a bilinear surface in an additive color space such as XYZ or RGB, as shown in FIGURE 2.
- a point 42 at g 0 corresponds to the background color (e.g., the color of the paper on which the duotone image will be printed)
- points 44 and 46 at g j and g 2 correspond to the pure ink colors that are used to print the duotone image
- a point 48 at g ] 2 corresponds to the combination of the two pure ink colors, i.e., the darkest color that can be produced by combining the two ink colors.
- the variables ctj and a 2 specify distances along edges 50 and 52, respectively, of the duotone gamut. Finding the Duotone Gamut
- the duotone gamut is fully specified by the Neugebauer model given the printing primaries go, gj, g 2 and g l 2 .
- spectral reflectance data for inks and papers were obtained using a COLORTRONTM spectrophotometer.
- the COLORTRONTM software provides data for PANTONE ® ink sets.
- the color of inks printed on a selected paper was estimated. Also estimated were the color of two inks superimposed on the selected paper.
- a simple model was used to approximate the effect of printing ink on a selected paper.
- the data for a layer of ink or paper can be expressed in two parts: an overall reflectance spectrum R and a Fresnel reflectance spectrum F.
- the overall reflectance spectrum indicates how much light of each wavelength is reflected back by the layer and can be directly measured with a spectrophotometer.
- the Fresnel information indicates how much light of each wavelength bounces off the surface of the layer without entering the layer. Inks act very much like filters, which are purely subtractive layers. A paper acts like an opaque layer. This simple behavior enables the layer composition to be approximated by multiplying reflectance spectra and adjusting for Fresnel effects. To approximate the result of superimposing a subtractive layer on another layer/, the Fresnel component is removed from each layer's overall reflectance, the thus altered spectra are multiplied, and the Fresnel reflectance of the top layer is added back to the result:
- the Fresnel spectrum of an ink is approximated by the reflectance spectrum of black ink.
- black absorbs nearly all incident light thus, any reflectance from a layer of black ink is primarily due to a Fresnel effect at the surface.
- the same Fresnel spectrum is used for paper, and any Fresnel effect between ink and paper is ignored.
- the layering model described above does not completely solve the problem, as the measured spectral reflectance data for an ink includes information about the stock paper on which the ink was originally printed. To compute the result of removing one layer from another, the above equations were simply inverted:
- the printing primaries g 0 , g ⁇ , g 2 , and g l 2 can be determined by first converting the appropriate spectral quantities to XYZ or RGB coordinates. Further details of the mapping procedure are discussed below. Goals of Duotone Mapping
- a key aspect of the present invention is the mapping that transforms the colors in the full color image onto the duotone gamut.
- the fundamental tradeoff in the present case is between mapping colors from the full color image exactly and maintaining overall relationships between the colors.
- a preferred embodiment of the present invention places more importance on overall relationships than on exact matches of color, and weighs certain relationships more heavily than others.
- the basic idea behind the mapping technique employed is to define an orthogonal axis system for each duotone gamut, then transform the colors of the full color image along two orthogonal directions and use a parallel projection along the third orthogonal direction.
- the choice of directions is clearly critical to the effectiveness of the mapping process and corresponds to preserving certain predetermined relationships between colors in the full color image at the expense of other relationships.
- the choices made for the mapping procedure in the preferred embodiment are as follows:
- the eye is more sensitive to light at some wavelengths than others.
- the luminance-efficiency curve which describes the relationship between wavelength and visual sensitivity, corresponds to a direction in a three-dimensional color space. Preserving separation of image colors along this direction of greatest sensitivity, called the luminance direction, is the primary goal of the preferred embodiment in the duotone mapping procedure.
- the Y axis of the XYZ color space corresponds exactly to the luminance direction, and therefore, Y is the direction of the first transformation.
- the preferred embodiment preserves in the mapping procedure is separation in the direction of most color variation on the duotone gamut.
- the curve on the gamut between the two individual ink primary colors selected describes the widest variation in color achievable with the selected paper and ink colors.
- the vector g 2 — g j is the ideal direction for the second transformation.
- the duotone mapping requires an orthogonal axis system, and the Y axis has already been chosen. Therefore, g 2 —g ⁇ is orthogonalized with respect to Y and the resulting ink-spread direction (or color variation axis) S is used as the direction of the second transformation.
- the duotone mapping takes image colors C / , . . ., c n and maps them to colors c. , . . ., c n on the duotone gamut.
- the mapping of image color c. takes place in three steps, with each step affecting a different orthogonal component of c r
- the components are as follows: c ⁇ ⁇ c - Y c - ⁇ c, - s c' ' ⁇ c - P
- the first transformation applied to the image colors is a mapping along Y to bring all colors within the full color image within the luminance range of the current duotone gamut.
- this mapping could be any monotonically increasing function, for the sake of simplicity a linear function is used. If c is the y- value of the original (full color) image color c catering and c is the y- value of the transformed color, the luminance transformation can be written as follows:
- FIGURE 4 shows a set of image colors (represented by black dots 60) for a full color image before and after their luminance values have been transformed to lie within the range of luminance values available in a typical duotone gamut 62, i.e., transformed relative to the Y luminance axis of orthogonal axes 64.
- a color space 66 illustrates the luminance range of image colors 60 before the luminance transformation.
- a color space 66' illustrates the range of the image colors after the luminance transformation; the range has been reduced by the luminance transformation so that relative to the luminance axis, the image colors fall within the luminance extents of the duotone gamut.
- the second transformation is along the ink-spread (color variation) axis S.
- This transformation depends upon luminance, since at some luminance values along the Y axis, the duotone gamut is wide and at others it consists of a single point.
- luminance value y between y mi ⁇ and j> max .
- the values s 0 and *?, can be defined to be the .y-values of the points found by intersecting the edges of the duotone gamut with a plane of constant luminance y .
- the ink-spread transformation at luminance value y brings the s-values of all image colors with luminance value y into the range [i 0 , ⁇ J .
- FIGURE 5 illustrates the effect of an ink-spread (color variation) transformation on a set of colors resulting from the transformation to the luminance range of the duotone gamut.
- the color variation of the colors from the full color image is shown in a color space 76 relative to a duotone gamut 72 before the color variation transformation.
- a color space 76' shows the reduced range of color variation of colors 70' so that the lie within the color variation extents of a duotone gamut 72, relative to the S axis.
- the non-uniformity along Y is handled by separating colors into bins according to -value and calculating a different transformation for each bin.
- the coherence among colors in most natural images prevents this discrete approach from introducing noticeable discontinuities into a duotone image.
- the ink-spread (color variation) transformation can be any monotonically increasing function that maps the s- values of image colors to the s- values available on the duotone gamut. Both a simple linear mapping and a more complex mapping, based on Bezier curves, are discussed below. Linear Mapping
- FIGURE 6A An example of linear ink-spread transformation for a single luminance bin is illustrated in FIGURE 6A.
- a line 80 defines the linear ink-spread transformation from a color c to a color ; ' s for one luminance bin.
- Bezier-Curve Mapping The linear mapping given above does not attempt to preserve the s-values of full color image colors, despite the fact that many such color values may be available in the duotone gamut. Instead, the linear mapping preserves the relationships between .y-values of the full color image colors. At the other extreme, each j-value could be mapped to the closest value in the interval of available values [i 0 , i ⁇ ] , thereby accurately reproducing some colors while clamping others to the interval endpoints.
- the preferred embodiment of the present invention preserves some of the benefits of both these alternatives.
- a mapping based on Bezier curves is implemented, as illustrated by a Bezier curve 82 in FIGURE 6B for a typical luminance bin.
- the Bezier-curve mapping is only described qualitatively. As with the linear mapping, the two endpoints of the curve are constrained to map -y min to s mm and * s max to * max . However, because only two cubic Bezier curves are used that meet with C continuity, there are five additional control points with which the behavior of the mapping process can be altered. These additional degrees of freedom are utilized to meet the constraints that follow. First, the slope of the B ⁇ zier-curve mapping at either end (controlled by Bj and is constrained to be zero, while the tangent at the middle of the curve (controlled by a segment B - B° ) is constrained to be parallel to the line (not shown) from B° to B ⁇ .
- the location of this center constraint is determined by intersecting the line from g to g, 2 with a plane of constant luminance y .
- the constraint at the center of the Bezier curves prevents colors that are closer in hue to one ink color from mapping to the ink color on the opposite side of the duotone gamut.
- the preferred implementation of the Bezier-curve mapping process relies on a lookup table in order to efficiently transform a value c. to a new value c- .
- the table corresponding to each luminance bin is determined before any colors of the full color image are transformed.
- a Bezier curve is evaluated at a large number of parameter values, and the resulting s, sj coordinates are stored in a table. Then, to map a value c- , it is only necessary to find the correct interval of s- values and use linear interpolation to approximate the result c, v . Determining the Projection
- FIGURE 7 illustrates the result of projecting a set of colors for a full color image onto a duotone gamut. Parallel Projection onto a Bilinear Surface
- the first dot product can be solved for a 2 in terms of a ⁇ to obtain:
- a flow chart in FIGURE 19 illustrates the logical steps employed for mapping colors from a full color image to a duotone gamut. From a start block, the logic proceeds to a block 140 that provides for converting the RGB data that define each color in the full color image to the XYZ color space. To simplify handling of the color data, an octree of the image colors is built in a block 142. A Y basis vector (luminance) is then set equal to the or Y axis of the XYZ color space in a block 144.
- an S basis vector for ink spread or color variation is set equal to a line that is perpendicular or orthogonal to the Y basis vector and is closest to a line through the two ink colors selected for the duotone, g, and g 2 . It will be recalled that these colors are at opposite sides of the duotone gamut.
- the P basis vector is determined by taking the cross product of the Kand the S basis vectors in a block 148.
- a block 150 the preferred embodiment calls for creating 256 bins of lookup tables for the S axis Bezier mapping of color variation to the duotone gamut.
- a block 152 provides for setting c to a first color in the octree created in block 142.
- the procedure linearly maps the Y component of the current color c to fit within the minimum and maximum luminance constraints of the duotone gamut, i.e., between g 0 and gj 2 and the minimum and maximum luminance components of the colors in the full color image.
- a block 156 the ink spread or color variation component of c along the S basis axis is mapped to the duotone gamut values using the S axis Bezier mapping tables created in block 150.
- c is projected onto the duotone gamut along the P axis, while simultaneously solving for a, and a 2 , to determine the duotone ink separations.
- a decision block 160 determines if there are any more colors in the octree to be processed, and if not, the mapping procedure terminates in a block 162. However, if more colors remain, a block 164 provides for set c to the next color in the octree. The logic then loops back to block 154 to map that color into the duotone gamut. Selecting Inks
- the duotone mapping described above assumed that two inks were given. In the more general cases, neither ink or just one ink is specified by the user.
- the goal of the software program comprising the present invention is to find one or more good pairs of ink colors for producing a duotone of a given full color image, in addition to finding the halftone separations for those colors.
- a good pair of ink colors is one for which the duotone mapping process produces an image that is as close as possible to the original full-color image.
- the "closeness of two images” is defined as the pixel-wise Z distance measured in a perceptually uniform color space.
- Simulated Annealing is a heuristic optimization technique designed to avoid local minima. Transitions from a current state to another state are generated randomly and accepted with some probability. This "acceptance probability" depends both on the relative scores of the two states, as rated by the objective function, and on the value of a control parameter T. Unfavorable moves are likely when T is high, but are accepted with decreasing probability as T decreases.
- cooling schedule describes the rate at which T decreases and the number of moves made at each value of T.
- a state consists of a pair of inks of different color, each of which has a set of neighbor inks. Taken together, the neighbor sets describe a fully connected graph. The set of legal moves from a state is the set of all possible moves to neighbor ink pairs from a given ink pair. Simulated annealing is an ideal optimization technique for the present problem. A heuristic technique must be used because most interesting ink sets, such as the PANTONE ® inks, contain hundreds of inks. In addition, preliminary experiments indicated that the objective function for this problem has many local minima. Finally, the large number of parameters associated with simulated annealing allows the optimizer to be tuned to meet the needs of the problem. In particular, by adjusting the cooling schedule and starting conditions, the optimizer is enabled to find several relatively deep local minima instead of a single global minimum. This adjustment is useful because it allows the software program to present several alternative choices of ink color pairs to the user.
- the simulated annealer uses a low-resolution version of the color information present in the original full color image.
- Such low-resolution information can be obtained either by quantizing the colors in the original full color image or by reducing the size of the original full color image.
- the low-resolution information is then provided to the duotone mapping step instead of the original image colors, to evaluate the results, so that the user can choose between several suggested good pairs of ink colors.
- simulated annealing arises from the similarity of the process to that used for annealing a metal by heating the metal to an elevated temperature and then cooling it according to a cooling schedule.
- the annealing process is initialized by setting a counter N to 1 in a block 170.
- a decision block 172 determines if the counter N is greater than a predefined variable, "NSUGGESTIONS" In the preferred embodiment of the present invention, this variable is equal to seven, indicating that the simulated annealing process should return seven suggested pairs of ink colors. However, other values can be set for NSUGGESTIONS as required for a particular application.
- the process terminates at a block 174. If the counter is less than the predetermined variable, the logic proceeds to a block 176, which sets a variable T to a variable INITIALTEMP.
- variable INITIALTEMP has a relatively large value and corresponds to the original elevated temperature of a metal being annealed, or in the case of selecting colors, the variable simply indicates a starting point for the process.
- a block 178 set a variable P to represent a pseudorandom pair of ink colors arbitrarily selected from the full set of ink colors available for producing the duotone image.
- an error is determined for the use of the P pair of ink colors to reproduce the full color image as a duotone image. This error is simply a measure of the distance between each color in the full color image and its corresponding color in the duotone image produced using the P pair of ink colors.
- a block 182 provides for setting a variable Q equal to a neighbor of P, i.e., a pair of ink colors in the vicinity of the P ink colors.
- the process determines the error that arises in using the Q pair of ink colors to reproduce the full color image as a duotone image.
- a decision block 186 determines if there is another neighbor pair of ink colors relative to P, and if so loops back to block 182 to repeat the steps from that point in the logic. If not, the logic proceeds to a block 188, in which a variable R is set to a pseudorandom real number.
- a decision block 190 determines if the product R*T is less than a predefined variable THRESHOLD.
- a block 192 sets P to an inferior neighbor of Q. However, if the product in decision block 190 is less than THRESHOLD, a block 194 sets P to the best neighbor Q. After block 192 or block 194, a block 196 decreases T based on a predefined cooling schedule.
- a decision block 198 determines if the new value of T is less than or equal to zero. If not, the logic loops back to block 182 to repeat the steps below that point. However, an affirmative response to decision block 198 leads to a block 200, which saves the pair P of ink colors in a suggestion list and increments the counter N. The logic then loops back to decision block 172 to determine if the desired number of suggestions has been achieved, and if not repeats the steps starting at block 176. To summarize, the simulated annealing process attempts to find a local minima of error resulting from using a pair of inks to reproduce the full color image as a duotone.
- clustering of image colors can be performed as a preprocessing step.
- Clusters of small size and large average distance from other clusters are marked as outlying clusters.
- Colors that have been identified as members of outlying clusters are ignored when calculating the ink-spread (color variation) transformation.
- the rationale is that such outlying colors matter less to the overall full color image, and that mapping them well at the expense of more prevalent colors to produce the duotone image is not justified.
- Colors that are ignored in calculating the ink-spread transformation may not project onto the duotone gamut. Each such color is transformed to a gray of the appropriate luminance, and that gray is then projected onto the gamut.
- Full-color printing relies on three colored inks — cyan, magenta, and yellow — that combine to make black.
- a black halftone separation is usually printed in addition to the three color separations in a full color process. Adding a black separation permits denser blacks than the three colors can produce, allows more detail to be expressed in shadowed areas, substitutes inexpensive black ink for more expensive colored inks, and avoids a thick accumulation of ink in each black or very dark portion of the full color image.
- Adding a black separation to duotone printing offers a further benefit: for full color images with a wide range of luminance values, the two-colored inks no longer need to be chosen so that their combination is close to black. Instead, the two ink colors can be chosen to reproduce the full color image's hues, while the black ink permits fine gradations in luminance to be achieved in the duotone image.
- a black-enhanced duotone gamut 100 is a volume bounded by four bilinear surfaces, (g 0 , g black), (g ⁇ g 2 , black), (g j , g l 2 , black), (g 2 , g l 2 , black), and one bilinear surface, as illustrated in FIGURE 8.
- black enhancement can be implemented as a simple extension to the present invention using the following steps:
- a full color image 110 is represented by dots 1 12 in a color space 1 14.
- An image 116 and a corresponding color space 114' illustrate the original image after black has been removed.
- a duotone image 118 is then produced from image 116 as described above; it is based on a duotone gamut 120, as shown in a color space 122.
- a black-enhanced duotone image 124 and its corresponding duotone gamut 120' are illustrated, to show the improved luminance achieved by adding black ink to the duotone printing process.
- the amount of black that should be used is determined by comparing the duotone colors to the original colors in the full color image. Because the primary emphasis is on preserving the luminance of full color image colors, the goal is to match the luminance of the corresponding color in the original full color image with the color that will be used instead in the duotone image. However, the complete range of original luminance values cannot be reproduced; instead an attempt is made to match a luminance scaled to lie between that of the paper color and that of the black ink that will be used for printing the duotone image. For each color c in the duotone image, a line segment is created from that color to the position of black ink. The position of c is then shifted toward black until it achieves the desired luminance at a point 132, as illustrated in FIGURE 10B. The amount of shifting required along the line through black determines the amount of black to print. Minimized Hue Difference
- an optional second pass is made over the duotone gamut, performed after the desired pair of ink colors has been selected. During the second pass, a pixel-by-pixel comparison of the duotone and the original image is performed, to enable the perceptual hue difference of each pixel to be determined. Hues are measured as hue angles in a perceptually uniform color space.
- a plane perpendicular to L* axis and passing through a particular brightness value contains a disk of all the hues present at that brightness, ranging from gray at the center to saturated colors on the edge.
- the perceptual hue difference between two colors is the difference between the hue angles of the colors.
- the procedure used for reducing hue differences in the present invention proceeds by desaturating (moving toward gray) each pixel in the original full color image by an amount parameterized by the magnitude of the hue difference computed for that pixel.
- the duotone mapping process is then applied to the grayed-out image.
- graying-out parts of the original full color image may improve the ink-spread (color variation) transformation by bringing s mi matter and s max closer to s min and * s max . Effectively, minimizing hue difference treats some potentially significant image colors like outliers, sacrificing them so that other colors will be mapped better.
- the paper used for printing a duotone image need not be white. For an original full color image without much white, using a colored paper can greatly improve a duotone image reproduction by providing an additional color essentially for free.
- a preferred embodiment of the present invention optionally enables the user to specify a paper color or leave the choice of paper to be automatically determined so as to optimize the duotone image reproduction of a full color image.
- the simulated annealing algorithm is modified to select a paper color by extending the definition of a state to include two inks and a paper color.
- duotone images were printed on a printing press and the results compared to reference prints of the full color images. While ordinarily a reproduction should look as much as possible like a photograph or an image displayed on a monitor, to evaluate the present invention for printing duotone image, duotone prints were compared to four-color process prints of the original full color image.
- RGB correction function was used. Data for the RGB correction was generated by printing (on a four-color press) a square for each color in a regular three-dimensional grid of colors spanning the RGB cube. Each printed square was scanned using a spectrophotometer and the spectral data were then converted to an RGB color. For this set of colors, a mapping was constructed from intended RGB values to actual printed RGB values. Using piecewise-trilinear interpolation between these discrete colors, any given RGB color can be transformed to the corresponding RGB color that four-color process printing would produce.
- a second aspect of the color printing experiments also required color correction.
- the Neugebauer model is not entirely accurate in its prediction of colors obtained by halftoning two colors of ink. Therefore, in keeping with the empirical spirit of printing, an empirical correction method was developed for adjusting duotone separations.
- This duotone correction is similar to the RGB correction, but it was necessary to measure data for only two dimensions. Using the two selected colors of ink, a regular grid of values for ⁇ 7 and a 2 were printed. Once again, the RGB color of each square in the grid was measured. Locating each measured RGB color on the duotone gamut associates intended percentages with printed percentages of inks. Using bilinear interpolation, a mapping from intended amounts to actual printed amounts was constructed. Applying the inverse of this function to a pair of separations before printing compensates for the simplicity of the Neugebauer model.
- FIG. 11 A Cezanne printed with four-color process inks (FIGURE 11 A) and as three duotone images.
- the traditional duotone was created using Adobe PHOTOSHOPTM.
- Example 2 shows a photograph of a koala printed in process color in FIGURE 12A and as a duotone image in FIGURE 12B.
- Example 3 depicts a painting by Renoir in full process colors (FIGURE 13 A) and as two duotones. The first duotone of the Renoir painting (FIGURE 13B) uses the same pair of user-selected inks as the duotone of the koala photograph in FIGURE 12B. Choosing an unrelated pair of inks for the second duotone of the Renoir painting results in a very different, but still successful reproduction in FIGURE 13C.
- Examples 4, 5, and 6 show three portrait photographs printed in full process colors (FIGURES 14A, 15 A, and 16A, respectively) and as duotones (FIGURES 14B, 15B, and 16B, respectively). All three duotones are printed with blue and orange-brown inks that were selected by the optimizer process for the photograph in Example 4 (FIGURE 14A).
- Example 7 shows a photograph of a sunset in full process color (FIGURE 17A) and as a black-enhanced duotone printed with hand-picked inks (FIGURE 17B). Viewed on a computer monitor, the original image contains colors not present in the full color process gamut. These colors are better achieved in a duotone that has not undergone the correction described in the previous section. Using the same inks, an uncorrected black-enhanced duotone was as the final duotone image (FIGURE 17C) in the series.
- Example 8 shows a painting by Schiele printed in full process color (FIGURE 18A) and as a duotone image on yellow paper with optimizer-selected inks (FIGURE 18B). Using colored paper allows the three dominant hues (yellow, red, and green) present in the original image to be reproduced.
- FIGURE 21 a generally conventional graphic workstation 230 is illustrated, which is suitable for use in practicing the present invention, i.e., workstation 230 comprises a system on which the present invention is implemented.
- the workstation includes a processor chassis 232 in which are mounted a hard drive 236 and, optionally, a floppy disk drive 234.
- a motherboard within the processor chassis is populated with appropriate integrated circuits (not shown) and a power supply (also not shown).
- a monitor 238 is included for displaying graphics and text generated by software programs executed by the workstation, and more specifically for displaying images that are processed and produced by the present invention.
- a mouse 240 (or other pointing device) is connected to a serial port (or to a bus port) on the rear of processor chassis 232, and signals from mouse 240 are conveyed to the motherboard to control a cursor and to select text, menu options, and graphic components displayed on monitor 238 in response to software programs executing on the workstation, including the software program implementing the present invention.
- a keyboard 243 is coupled to the motherboard for entry of text and commands that affect the running of software programs executing on the workstation.
- Workstation 230 also optionally includes a compact disk-read only memory (CD-ROM) drive 247 into which a CD-ROM disk may be inserted so that executable files and data on the disk can be read for transfer into the memory and/or into storage on hard drive 236 of workstation 230.
- CD-ROM compact disk-read only memory
- workstation 230 is coupled to a local area and/or wide area network and is one of a plurality of such workstations on the network. In many cases, files accessed by these workstations will be stored on a server (not shown) accessed over the network.
- FIGURE 22 illustrates some of the functional components that are included.
- the motherboard includes a data bus 233 to which these functional components are electrically connected.
- a display interface 235 generates signals in response to instructions executed by a central processing unit (CPU) 253 that are transmitted to monitor 238 so that graphics and text are displayed on the monitor.
- a hard drive/floppy drive interface 237 is coupled to data bus 233 to enable bidirectional flow of data and instructions between data bus 233 and floppy drive 234 and/or hard drive 236.
- Software programs executed by CPU 253 are typically stored on either hard drive 236, or on a floppy disk (not shown) that is inserted into floppy drive 234.
- the software program comprising machine language instructions that cause the CPU to implement the present invention will likely be distributed either on such a floppy disk, or on a CD-ROM disk. Alternatively, the software program may be distributed over the Internet.
- a serial/mouse port 239 is also bidirectionally coupled to data bus 233, enabling signals developed by mouse 240 to be conveyed through the data bus to CPU 253.
- a CD-ROM interface 259 connects CD-ROM drive 247 to data bus 233.
- the CD-ROM interface may be a small computer systems interface (SCSI) type interface or other interface appropriate for connection to and operation of CD-ROM drive 247.
- SCSI small computer systems interface
- a CD-ROM drive is indicated, it is also contemplated that other types of optical storage devices and appropriate interface might also be used.
- a keyboard interface 245 receives signals from keyboard 243, coupling the signals to data bus 233 for transmission to CPU 253. Coupled to data bus 233 is a network interface 250 (which may comprise, for example, an EthernetTM card for coupling the workstation to a local area and/or wide area network).
- a network interface 250 (which may comprise, for example, an EthernetTM card for coupling the workstation to a local area and/or wide area network).
- software used in connection with the present invention may optionally be stored on a remote server and transferred to workstation 230 over the network to implement the present invention.
- Memory 251 includes both a nonvolatile read only memory (ROM) in which machine instructions used for booting up workstation 230 are stored, and a random access memory (RAM) in which machine instructions and data are temporarily stored when executing application programs, such as the software program implementing the present invention.
- ROM read only memory
- RAM random access memory
- a key aspect of the method employed by the present invention is the duotone mapping: the transformation of a set of scattered image colors for a full color image onto a surface (of the duotone gamut) in three-dimensional color space.
- the mapping preserves relationships between image colors at the expense of matching exact colors. It is clear that many other mappings are possible; some of the difficulties that exist with mapping in general and with alternatives to the method used in a preferred embodiment of the present invention are as follows: Finding the closest color.
- the obvious problem with the approach of mapping an image color to the closest point on the duotone gamut is that out-of-gamut image colors will be clamped. While clamping may be acceptable for certain images and duotone gamuts, in general clamping results in artificial discontinuities and a loss of information.
- a more fundamental difficulty with an orthogonal projection is the absence of an obvious continuous mapping, since there are colors in the full color image for which there is no orthogonal projection onto the duotone gamut.
- the present invention might also apply to the more general problem of finding the best n ink colors (not limited to two) with which to reproduce an image.
- the algorithm may be extended to take advantage of psychophysical effects such as von Kries adaptation and simultaneous contrast. These effects may allow a user of the invention to effectively expand the printing gamut by tricking the eye into seeing colors that are not actually achievable.
- Another possible extension to the present invention is a system that facilitates the production of two-color brochures by optimizing over images, inks, and papers.
- the system would take several images as input and choose two inks, one paper, and a specified number of the images that would reproduce well with the selected inks and paper.
- the present invention has no sense of what parts of images are semantically or aesthetically important. Because the creation of a duotone image from a full color image frequently requires loss of color information, the approach taken in the above disclosed embodiment would benefit from user input indicating which colors in the original image are most important to preserve. It is further contemplated that the duotone mapping process of the present invention be combined with the artistic screening approach to halftoning presented by Ostromoukhov and Hersch, "jArtistic Screenings" Proceedings of SIGGRAPH 95, pages 219-228, ACM, New York, 1995.
Abstract
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1076883A1 (en) * | 1999-03-11 | 2001-02-21 | Lockheed Martin Missiles and Space | Method and apparatus to compress multi-spectral images to a single color image for display |
EP1170144A2 (en) * | 2000-06-29 | 2002-01-09 | Fujicopian Co., Ltd. | Method for forming image by thermal transfer |
DE10247212A1 (en) * | 2002-10-10 | 2004-04-22 | Klaus Kettner | Preparing image material for use in two-color printing involves taking account of mixing properties of two printing colors used for relevant original color, unlike conventional duplex printing |
US7433080B2 (en) | 2004-09-28 | 2008-10-07 | Toshiba Corporation | System and method for conversion of duotone images for display |
Families Citing this family (51)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB9619119D0 (en) * | 1996-09-12 | 1996-10-23 | Discreet Logic Inc | Processing image |
US6115493A (en) * | 1998-08-05 | 2000-09-05 | Xerox Corporation | Technique for fast computation of highlight color mappings |
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US6459435B1 (en) | 2000-01-11 | 2002-10-01 | Bluebolt Networks, Inc. | Methods, systems and computer program products for generating storyboards of interior design surface treatments for interior spaces |
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US7054031B2 (en) * | 2001-06-22 | 2006-05-30 | Weyerhaeuser Company | Color reproduction process |
US7215813B2 (en) * | 2001-12-03 | 2007-05-08 | Apple Computer, Inc. | Method and apparatus for color correction |
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US20030176281A1 (en) * | 2002-03-13 | 2003-09-18 | Hultgren Bror O. | Choice of chromophores in two color imaging systems |
US7972981B2 (en) * | 2002-03-15 | 2011-07-05 | Fiberweb, Inc. | Microporous composite sheet material |
JP4400706B2 (en) * | 2002-11-25 | 2010-01-20 | 富士ゼロックス株式会社 | Color data accuracy calculation method, color data accuracy calculation device, color processing method, color processing device, color data accuracy calculation program, color processing program, storage medium |
WO2004052641A1 (en) * | 2002-12-10 | 2004-06-24 | Saint Gobain Technical Fabrics | Breathable, waterproofing, tear-resistant fabric |
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US7466687B2 (en) * | 2003-04-28 | 2008-12-16 | International Business Machines Corporation | Packet classification using modified range labels |
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US7583837B2 (en) * | 2004-01-15 | 2009-09-01 | Xerox Corporation | Method and system for preparing grayscale image files for highlight printing on a four color printer |
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US20050217937A1 (en) * | 2004-04-05 | 2005-10-06 | Rohlf Bradley A | Retractable safety device |
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DE102004044647A1 (en) * | 2004-09-15 | 2006-03-30 | OCé PRINTING SYSTEMS GMBH | Method and apparatus for converting source image data into target image data |
US20060188390A1 (en) * | 2005-02-24 | 2006-08-24 | Galloway Richard M | Fumigation tarp |
US20060268297A1 (en) * | 2005-05-25 | 2006-11-30 | Lexmark International, Inc. | Method for constructing a lookup table for converting data from a first color space to a second color space |
US20070084542A1 (en) * | 2005-10-19 | 2007-04-19 | Durakon Industries, Inc. | Process and apparatus for forming stretched paint films and articles formed using same |
US20070281562A1 (en) * | 2006-06-02 | 2007-12-06 | Kohlman Randolph S | Building construction composite having one or more reinforcing scrim layers |
US7738142B2 (en) * | 2006-11-15 | 2010-06-15 | Eastman Kodak Company | Estimating color of a colorant deposited on a substrate |
US20080219303A1 (en) * | 2007-03-02 | 2008-09-11 | Lucent Technologies Inc. | Color mixing light source and color control data system |
US20080232884A1 (en) * | 2007-03-22 | 2008-09-25 | Cadlink Technology Corporation | Method for printing onto coloured substrates |
US7984591B2 (en) * | 2007-08-10 | 2011-07-26 | Fiberweb, Inc. | Impact resistant sheet material |
US8544218B2 (en) * | 2008-03-27 | 2013-10-01 | Dell Seven, Inc. | Acoustically insulating product |
US20100290721A1 (en) * | 2009-05-13 | 2010-11-18 | E. I. Du Pont De Nemours And Company | Industrial bag having a fluid drainage layer |
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US20140063047A1 (en) * | 2012-09-01 | 2014-03-06 | Garrett M. Johnson | Duotone effect |
US8861053B2 (en) * | 2012-11-02 | 2014-10-14 | Electronics For Imaging, Inc. | Method and apparatus for automated generation of a white ink separation out of CMYK data or RGB print data |
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EP3928997A1 (en) * | 2020-06-24 | 2021-12-29 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Method for creating a colored laser marking |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4903048A (en) * | 1988-11-28 | 1990-02-20 | Xerox Corporation | Simulated color imaging using only two different colorants/toners |
US5237517A (en) * | 1990-08-29 | 1993-08-17 | Xerox Corporation | Color printing having a highlight color image mapped from a full color image |
US5297058A (en) * | 1990-08-29 | 1994-03-22 | E. I. Du Pont De Nemours And Company | Method for creating multicolored halftone reproductions from continuous tone monochrome originals |
US5398120A (en) * | 1993-12-16 | 1995-03-14 | Microsoft Corporation | Ordered dither image rendering with non-linear luminance distribution palette |
Family Cites Families (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL271149A (en) * | 1960-11-08 | 1900-01-01 | ||
US3532589A (en) * | 1965-04-12 | 1970-10-06 | Du Pont | Differentially bonded non-woven sheet |
US4684568A (en) * | 1986-04-21 | 1987-08-04 | E. I. Du Pont De Nemours And Company | Vapor-permeable liquid-impermeable fabric |
US4929303A (en) * | 1987-03-11 | 1990-05-29 | Exxon Chemical Patents Inc. | Composite breathable housewrap films |
JPH07358B2 (en) * | 1988-11-09 | 1995-01-11 | 日本石油化学株式会社 | Weather-resistant reticulated split membrane, its nonwoven fabric, and its manufacturing method |
US5013599A (en) * | 1989-09-29 | 1991-05-07 | E. I. Du Pont De Nemours And Company | Composite fibrous polyethylene sheet |
US5047842A (en) * | 1989-11-03 | 1991-09-10 | The Trustees Of Princeton University | Color image display with a limited palette size |
JP2983584B2 (en) * | 1990-07-17 | 1999-11-29 | 日本石油化学株式会社 | Method for producing reticulated nonwoven fabric |
JP2988991B2 (en) * | 1990-10-04 | 1999-12-13 | 日本石油化学株式会社 | Nonwoven fabric, method for producing slit-shaped band used for the same, and slit forming roll used for the method |
US5182162A (en) * | 1990-10-24 | 1993-01-26 | Amoco Corporation | Self-bonded nonwoven web and net-like web composites |
US5185661A (en) * | 1991-09-19 | 1993-02-09 | Eastman Kodak Company | Input scanner color mapping and input/output color gamut transformation |
JP3517757B2 (en) * | 1994-04-27 | 2004-04-12 | 株式会社リコー | Image processing device |
US5611030A (en) * | 1994-09-16 | 1997-03-11 | Apple Computer, Inc. | Subjectively pleasing color gamut mapping in a color computer graphics system |
US5644509A (en) * | 1994-10-07 | 1997-07-01 | Eastman Kodak Company | Method and apparatus for computing color transformation tables |
US5763336A (en) * | 1996-01-24 | 1998-06-09 | E. I. Du Pont De Nemours And Company | Bulky composite sheet material |
-
1997
- 1997-07-28 US US08/901,301 patent/US6046118A/en not_active Expired - Fee Related
- 1997-08-01 AU AU39619/97A patent/AU3961997A/en not_active Abandoned
- 1997-08-01 WO PCT/US1997/012835 patent/WO1998005510A2/en active Application Filing
- 1997-08-01 US US08/904,945 patent/US5982924A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4903048A (en) * | 1988-11-28 | 1990-02-20 | Xerox Corporation | Simulated color imaging using only two different colorants/toners |
US5237517A (en) * | 1990-08-29 | 1993-08-17 | Xerox Corporation | Color printing having a highlight color image mapped from a full color image |
US5297058A (en) * | 1990-08-29 | 1994-03-22 | E. I. Du Pont De Nemours And Company | Method for creating multicolored halftone reproductions from continuous tone monochrome originals |
US5398120A (en) * | 1993-12-16 | 1995-03-14 | Microsoft Corporation | Ordered dither image rendering with non-linear luminance distribution palette |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1076883A1 (en) * | 1999-03-11 | 2001-02-21 | Lockheed Martin Missiles and Space | Method and apparatus to compress multi-spectral images to a single color image for display |
EP1076883A4 (en) * | 1999-03-11 | 2007-01-03 | Lockheed Martin Missiles And S | Method and apparatus to compress multi-spectral images to a single color image for display |
EP1170144A2 (en) * | 2000-06-29 | 2002-01-09 | Fujicopian Co., Ltd. | Method for forming image by thermal transfer |
EP1170144A3 (en) * | 2000-06-29 | 2002-10-02 | Fujicopian Co., Ltd. | Method for forming image by thermal transfer |
DE10247212A1 (en) * | 2002-10-10 | 2004-04-22 | Klaus Kettner | Preparing image material for use in two-color printing involves taking account of mixing properties of two printing colors used for relevant original color, unlike conventional duplex printing |
US7433080B2 (en) | 2004-09-28 | 2008-10-07 | Toshiba Corporation | System and method for conversion of duotone images for display |
Also Published As
Publication number | Publication date |
---|---|
AU3961997A (en) | 1998-02-25 |
US6046118A (en) | 2000-04-04 |
WO1998005510A3 (en) | 1998-04-23 |
US5982924A (en) | 1999-11-09 |
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